1. Technical Field
This disclosure relates generally to controlling user functions and conserving power in electronic devices, and in particular, in mobile communication devices.
2. Description of the Related Art
Mobile devices such as smart phones and tablet PCs have become widely popular due to their portability and support of a wide variety of user functions. Recent designs provide integrated user functions, such as a camera function in conjunction with storing acquired photographs and videos, immediately searching for the acquired photographs or videos, etc. As newer models of mobile devices are equipped with relatively large displays, although they're still easily hand carried, a tradeoff in user controllability has arisen. For example, a notebook sized tablet can be held by one hand while the user touches the display with the same hand or the other hand; however, he/she may be unable to continue holding it stably due to the weight and size. This may cause a variety of problems, such as the user losing his/her grip of the mobile device, or causing a muscle injury.
To conserve battery power, conventional mobile devices change state from a normal state, in which the display has normal brightness, to a power save state in which the display is dimmed or shut off (the latter is referred to herein as a sleep state). The transition to the power save state is made after a predetermined elapsed time of not receiving any user input, such as a touch input command. This elapsed time is essentially a predicted time where the user is no longer actively viewing the display. To this end, a state control function is set under conditions set by default or by preference settings.
However, the set conditions may not always match a particular user's interaction with the mobile device. For example, the predetermined elapsed time that triggers the transition from normal mode to sleep mode is a fixed value, not adaptively varied according to the user's state or the environment. Therefore, the conventional mobile device may enter a power save or sleep mode at an undesirable time point, e.g. when the user still wants to use the device. In this case, the user must apply an additional operation to the mobile device, e.g., an awaking operation. The additional operation inconveniences mobile device users, and in particular, users of devices with larger displays which tend to be more actively utilized. Furthermore, if the elapsed time for transitioning to a power save mode is set too long, battery power is essentially wasted in the time period after the user stops viewing the display but prior to the elapsed time point.